1. Field of the Invention
The present invention relates generally to automated machine control, which can be configured for work order management involving multiple agricultural vehicles and crop fields, and in particular to a global navigation satellite system (GNSS) based agricultural spray boom height control system and method.
2. Description of the Related Art
Mobile equipment and machinery, including vehicles, agricultural equipment, open-pit mining machines and crop duster aircraft, are commonly guided and operationally controlled using global navigation satellite system (GNSS) components. Currently-available satellite positioning systems (SATPS) provide parallel and contour swathing for precision farming. For example, equipment can be guided or automatically steered along adjacent parallel path swaths, which can be offset from each other by approximately the vehicle width in a parallel path mode of operation.
Various GNSS-based navigation systems have been installed in ground-based vehicles. Systems using Doppler radar guidance systems can encounter positioning errors with the radar and latency. Similarly, gyroscopes and accelerometers (collectively inertial measurement units (IMUs) provide heading, roll and pitch measurements (e.g., XYZ headings). However, IMUs tend to encounter drift and bias errors requiring external attitude measurements for gyroscope initialization and drift compensation. Gyroscopes have good short-term characteristics but undesirable long-term characteristics, especially lower-cost gyroscopes, such as those based on vibrating resonators.
Similarly, inertial systems employing gyroscopes and accelerometers have good short-term characteristics but also suffer from drift. Existing GNSS position computations may include lag times, which may be especially troublesome when, for example, GNSS velocity is used to derive vehicle heading. Many existing GNSS systems do not provide highly accurate heading information at slower vehicle speeds. Therefore, what is needed is a low cost sensor system to facilitate vehicle swath navigation that makes use of the desirable behaviors of both GNSS and inertial units while eliminating or reducing non-desirable behavior. Specifically, what is needed is a means to employ low-cost gyroscopes (e.g., micro electromechanical (MEM) gyroscopes) which tend to provide good short-term, low-noise, high-accuracy positioning while minimizing inherent long-term drift.
Providing multiple antennas on a vehicle can provide additional benefits by determining an attitude of the vehicle from the GNSS ranging signals received by its antennas, which are constrained on the vehicle at a predetermined spacing. For example, high dynamic roll compensation signals can be output directly to the vehicle steering using GNSS-derived attitude information. Components such as gyroscopes and accelerometers can be eliminated using such techniques. Real-time kinematic (RTK) navigation can be accomplished using relatively economical single frequency L1—only receivers with inputs from at least two antennas mounted in fixed relation on a rover vehicle. Still further, moving baselines can be provided for positioning solutions involving tractors and implements and multi-vehicle GNSS control can be provided.
Providing additional antennas in combination with standard SATPS and GNSS guidance, as mentioned above, along with optional gyroscopes, can provide an effective method to increase GNSS positioning precision and accuracy. However, accuracy and precision can only improve the efficiency of working vehicles, such as those in the agricultural field, to a limited extent. Although such systems are able to track and guide vehicles in three dimensions, including along ridges and sloped-regions, errors may appear in other aspects of a working vehicle. For example, in an agricultural field-working situation where a tractor is towing an implement, the implement may slide on a sloped-region, or the tractor may list to one side or another when entering softer soil or rocky areas. This can happen repeatedly when a vehicle is guided around the same field, regardless of the precision of the guidance system in pre-planning a path. Thus, a system that can detect such changes in uniformity of a field as the vehicle traverses a path, and can remember those changes, can predict and re-route a more accurate and more economical path than a guidance system alone.
Conventional agricultural spraying operations are carried out over an entire field, everywhere the crop is planted. In contrast, environmental spraying allows the spraying of certain materials which require restrictions in the area of deposition due to potential toxicity or strength. The restrictions can include the distance from waterways and slope of the ground which can affect run-off and concentrations of deposits. In spray equipment with booms, maintaining uniform boom height over field surfaces during product application is important for uniform application rates and optimum product drift management relative to the targets, e.g., field crops. These systems are limited in performance due to their ability to look ahead and react with a spray vehicle traveling at a high rate of speed. In addition, these methods encounter issues when there are rapid changes in terrain or skips in crop canopy. The present invention addresses both issues.
GNSS-based precision application of agricultural inputs, such as pesticides, fertilizers and seeds, are commonly performed with large fleets of vehicles dispatched from common or networked home-base locations. Communication of mission planning information to all working vehicles, in real time, is paramount to efficiency. One piece of such information, which is a key to the present invention, is the terrain model, which can be created with specialized software using previously-logged field data containing highly precise positioning information from real-time kinematic (RTK) GNSS receivers. The logged data can be uploaded to the processing center from the logging vehicle through any data connection, although a wireless/remote connection is most desired for efficiency. Once processed, the terrain models can be dispatched from the home-base or processing center location to any vehicle via wireless data connection. The data is thus available to operators preparing to work fields using the boom height control system of the present invention. Using wireless data connectivity, the Internet (i.e., via the “Cloud”) enables efficient use of a boom height invention via the seamless transfer of the terrain model, which is a key component of the system.
Work order management functions for coordinating multiple machines at multiple remote locations can be accommodated with the present invention.
Previous spray boom height control systems include sonic sensors for measuring spray boom heights over ground surfaces and crop canopies.
Heretofore there has not been available a system and method with the advantages and features of the present invention.